Monte Carlo modeling of secondary electron imaging in three dimensions

John S. Villarrubia; Nicholas W. M. Ritchie; Jeremiah R. Lowney

doi:10.1117/12.712353

5 April 2007 Monte Carlo modeling of secondary electron imaging in three dimensions

John S. Villarrubia, Nicholas W. M. Ritchie, Jeremiah R. Lowney

Proceedings Volume 6518, Metrology, Inspection, and Process Control for Microlithography XXI; 65180K (2007) https://doi.org/10.1117/12.712353
Event: SPIE Advanced Lithography, 2007, San Jose, California, United States

Abstract

Measurements of critical dimensions (CDs), roughness, and other dimensional aspects of semiconductor electronics products rely upon secondary electron (SE) images in the scanning electron microscope (SEM). These images are subject to artifacts at the nanometer size scale that is relevant for many of these measurements. The most accurate measurements for this reason depend upon models of the probe-sample interaction in order to perform corrections. MONSEL, a Monte Carlo simulator intended primarily for CD metrology, has been providing the necessary modeling. However, restrictions on the permitted sample shapes are increasingly constraining as the industry's measurement needs evolve towards inherently 3-dimensional structures. We report here results of a collaborative project, in which the MONSEL physics has been combined with the 3D capabilities of NISTMonte, another NIST Monte Carlo simulator that was previously used principally to model higher energy electrons and x-rays. Results from the new simulator agree very closely with the original MONSEL for samples within the repertoire of both codes. The new code's predicted SE yield variation with angle of incidence agrees well with preexisting measurements for light, medium, and heavy elements. Capabilities of the new code are demonstrated on a model of a FinFET transistor.

Citation Download Citation

John S. Villarrubia, Nicholas W. M. Ritchie, and Jeremiah R. Lowney "Monte Carlo modeling of secondary electron imaging in three dimensions", Proc. SPIE 6518, Metrology, Inspection, and Process Control for Microlithography XXI, 65180K (5 April 2007); https://doi.org/10.1117/12.712353

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